Offshore mooring/loading system

ABSTRACT

A mooring system for connecting a vessel having an opening in its bow, to a fixed non-compliant offshore structure allows the moored vessel to weathervane 360 degrees around the structure while it is being loaded or while it tranfers fluids back to the production structure. The mooring system includes an outer boom pivotally mounted to the structure and an inner boom slidably mounted to the outer boom. The inner boom has an inboard end slidably mounted within the outer boom and a curved outboard end extending beyond the inner boom and defining an opening. The assembly of the inner and outer boom is articulated so that it may be placed in contact with a mooring receptacle of the vessel so that the opening in the inner boom is adjacent to mooring receptacle of the vessel. An elongated mating link is retained by the inner boom and extends through the aligned openings in the inner and in the bow of the vessel. Upon extension the elongated mating link is rotatably mounted with respect to the longitudinal axis of the inner boom. Upon all vessel movements, the inner boom remains in contact with the mooring receptacle of the vessel due to the rotatable connection between the elongated mating link and the inner boom. A shock absorption system mounted with the inner and outer boom resists tensile and compressive forces in a direction parallel to the longitudinal axis of the inner boom exerted by the vessel on the inner boom.

FIELD OF THE INVENTION

The field of the invention relates to offshore mooring/loading systemsfor temporarily moored tankers.

DESCRIPTION OF THE PRIOR ART

In the past, offshore mooring/loading systems for temporarily mooredtankers were limited to operation in ice-free areas. These systems weremounted on compliant structures and all made use of conventional softline mooring arrangements. These structures were usually single purposeloading terminals that required a separate production-storage facilityand typically transferred the crude from the production to loadingfacilities through submerged pipelines or the like. The crude oil wastransferred from the loading facility to the tanker via suspended orfloating oil lines. One such system is discussed in the May 1983 issueof Ocean Industry Magazine on page 12.

There has been little development in designs for mooring/loading systemsfor arctic areas. One of the known designs for arctic use included astorage terminal structure having an oil handling apparatus mounted tothe structure with a center swivel. This system was not useful forproduction platforms, since the topside equipment necessary for aproduction structure made the use of a 360° swivel impossible.Furthermore, even where such systems were practical they required asubmarine pipe network from the production platform(s) to the terminalloading platform(s).

Other systems have included a suspended perimeter trolley oil deliverysystem for transferring crude from an oil producing terminal to a mooredvessel. These systems are developed for ice-free areas. Although suchsystems enabled the tethered vessel to drift somewhat circumferentiallyabout the oil production terminal, a full 360° weather vaning capabilitywas not achieved. One inherent llmitation in such prior systems was dueto the weight of the crude delivery hose when full of crude. Any systemswhich required paying out and taking up long lengths of hose filled withcrude were limited by the capability of the equipment to deal with suchgreat weight.

The known systems described employed a soft catenary mooring line ratherthan direct contact between a loading/mooring boom and the vessel to beloaded. The use of a soft mooring line limited the load capacity of themooring systems and required the moored vessel to use continuous asternpower to keep off the loading structure.

BACKGROUND OF THE INVENTION

The apparatus of the present invention is designed to facilitate theberthing and loading of a shuttle tanker from a fixed non-compliantoffshore production/storage terminal, especially in a severe arcticenvironment. It is desirable to allow the connected tanker to weathervane without limit to either direction around the offshoreproduction/storage terminal. By permitting the moored vessel to weathervane around the terminal the mooring loads are greatly reduced by takingadvantage of the natural sheltering provided by the terminal structure.Furthermore, the telescoping boom arrangement of the present inventionprovides a compliant connection between the tanker and the platform tofurther reduce mooring loads by permitting first order motions of thetanker. First order motions are high frequency low amplitudeoscillations of the tanker due to environmental conditions.

Typically, offshore bottom founded production/storage gravity structuresdesigned for arctic service have a general conical profile below thewater level and have base diameters as large as 600 feet and more. Thesestructures may be placed in offshore locations with water depths of 60feet or more. Typical ice capable tankers used to load crude oil fromsuch production/storage terminals can be as long as 1,100 feet or more.The design of a mooring system must take into account the environmentalconditions anticipated when ice conditions appear as well as open waterconditions. Typically open water conditions are of a dynamic nature andtend to introduce large amplitude motions while the magnitude of theapplied forces is relatively small. Ice conditions introduce largeamplitude low frequency loading that results in higher stresses in thestructure but introduces relatively little motion.

During open water conditions mooring forces are generated due to wave,current and wind loading on the mooring vessel. During the colder monthsthe effect of ice on the moored vessel must be considered in the designof a mooring system. Empirical methods for calculating the loading ofice on vessels transiting through and ice field are known, as indicatedby G. P. Vance "A Scaling System for Vessels Modeled in Ice" Society ofNaval Architects and Marine Engineers, Proceedings, ICETECH 75,Montreal, Canada, April 1975. Analytical methods for calculating iceloads on vessels transiting through a broken or unbroken ice field arealso known as indicated by V. R. Milano, "Variation of Ship/IceParameters on Ship Resistance to Continuous Motion in Ice" and "ShipResistance to Continuous Motion in Ice" Society of Naval Architects andMarine Engineers, Proceedings, ICETECH 75, Montreal, Canada, April 1975.These methods have to be applied to moored vessels in an advancing icefield.

Taking into consideration the ice loads for an assumed ice thickness offifteen feet as well as wind and current loads the apparatus of thepresent invention has been analyzed with an expected total tensile loadon the boom of 4,600 kips applied along the centerline of the boom at anangle of inclination with the horizontal plane of twenty degreesmaximum. Although the moored vessel will use astern power and/or sidethrusters to the extent required to keep off the terminal structure,during transient conditions the vessel may apply some rideup load to thestructure. The apparatus of the present invention is suited to handlerideup or compressive loads on the order of 1,000 kips and a side loadof 500 kips.

The mooring/loading system of the present invention has the capabilityof year around unassisted mooring, demooring and loading of shuttletankers to a fixed production structure. The system is capable ofmaintaining the shuttle tanker moored during open water or iceconditions. First order vessel motions including vessel surge arecompensated for by the telescoping boom arrangement. The vessel ispermitted to continuously weather vane around the production structurewhile loading crude uninterruptedly. The mooring and loading apparatusaccommodates significant variation in the height of the ship-sidemooring connection above the mean sea surface, provides automaticemergency decoupling of the mooring and loading system, and furthermaintains the mooring boom with the loading lines clear of the seasurface. The apparatus of the present invention allows the mooringequipment to be enclosed when not in use and further provides fortracing and heating of weather exposed surfaces for de-icing purposes.The mooring system provides compensation for movement in the horizontaland vertical planes with a minimum impact on the terminal structure towhich it is connected. Finally, the mooring system of the presentinvention allows a safe and quick mooring/demooring procedure withoutassistance from service boats.

SUMMARY OF THE INVENTION

Briefly stated, the present invention provides a system for mooring avessel having mooring receptacle to a fixed non-compliant offshorestructure which permits the moored vessel to weather vane without limitin either direction around the structure while it is being loaded orwhile it transfers fluids back to the production structure. The mooringsystem includes an outer boom pivotally mounted to the structure and aninner boom slidably mounted within and extending from the outer boom.The inner and outer boom form a controlled, articulated assembly whichpermits an operator to place the boom in contact with the mooringreceptacle of an offloading vessel, so that the inner boom is adjacentthe mooring receptacle of the vessel suitably adapted to receive anelongated mating link. The interior of the inner boom defines a cavitythrough which fluid hoses and the like traverse. An elongated matinglink is retained by the inner boom and extends through the alignedopenings in the inner boom and in the bow of the vessel. The elongatedmating link, when extended from the outboard end of the inner boomfreely rotates with respect to the longitudinal axis of the inner boom.Thus, the inner boom remains in contact with the mooring receptacle ofthe vessel under all conditions due to the rotatable connection betweenthe elongated mating link and the inner boom. A shock absorption systemmounted with the inner and outer boom, in a direction parallel to thelongitudinal axis of the inner boom, resists tensile and compressiveforces exerted by the vessel on the inner boom. This system will exertincreasing resistance with increasing movement of the inner boom from amean position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overall elevational view of the offshore structure and thevessel illustrating the telescoping boom mounted to the offshorestructure;

FIG. 2 is a partial side elevational view of the A-frame illustratingthe location of the luffing apparatus thereon;

FIG. 3 is a front elevational view of the A-frame illustrating theposition of the luffing winch and the driven bogies,

FIG. 4 is a cutaway sectional elevation of the A-frame showing thedisposition of the fluid loading lines and fluid transfer lines therein;

FIG. 5 is a plan view of the A-frame illustrating the coupling anddecoupling of the fluid transfer lines to the outlets on the circularfluid loading header;

FIG. 6 is a cutaway sectional elevational view of the inner boom incontact with the bow of the vessel illustrating the facilities withinthe vessel for retaining the elongated mating link, and illustrating theloading arm on the inner boom for connecting the fluid loading lines andthe fluid transfer lines from the inner boom to the vessel;

FIG. 7 is a cutaway plan view of the elongated mating link shown withinthe outboard end of the inner boom;

FIG. 8 is a part cutaway plan view of the inner boom disposed within theouter boom illustrating the support of the inner boom within the outerboom and the disposition of the fluid loading lines and the fluidtransfer lines within the inner boom, outer boom and the A-frame;

FIG. 9 is a part cutaway elevational view of the inner boom, outer boomand A-frame shown in FIG. 8;

FIG. 10 is a sectional view taken along lines 10--10 of FIG. 8; and

FIG. 11 is a detailed plan view of the shock absorbing system shown inFIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The mooring system apparatus M, as shown in FIG. 1, allows a vessel V tobe moored to a fixed non-compliant offshore structure S. The mooringsystem M includes an outer boom B and an inner boom I adapted totelescope within outer boom B as will be more fully describedhereinbelow. Outer boom B is pivotally mounted to A-frame A. A luffingmeans L is mounted to A-frame A and permits outer boom B to pivot in asubstantially vertical plane as will be more fully describedhereinbelow. Inner boom I further includes a mating link E pivotallymounted to the outboard end of boom I. A-frame A is mounted to theoffshore structure S in a manner allowing vessel V to weather vanewithout a limit in either direction about offshore structure S whenvessel V is connected to inner boom I via elongated mating link E, aswill be more fully described hereinbelow.

Referring now to FIGS. 8, 9 and 11, system M includes a shock absorptionmeans C to dampen tensile and compressive forces exerted along thelongitudinal axis of inner boom I by vessel V, in the manner describedbelow. A fluid transfer means F is provided (FIGS. 4, 9) to allowtransfer of fluid in either direction from the offshore structure S tothe vessel V. A releasable engagement means R is mounted on vessel V toretain elongated mating link E within the bow of vessel V. Accordingly,when releasable engagement means R retains elongated mating link Ewithin the bow of vessel V, inner boom I is in contact with vessel V(FIG. 6). The pivotal connection between elongated mating link E andinner boom I allows inner boom I to remain in contact with vessel Vdespite all vessel movements.

As seen in FIGS. 2 and 3, A-frame A is an enclosed box girder structurehaving a pair of mouting lugs 10a to facilitate the pivotal mounting ofouter boom B via pin 10b mounted to lug 10a. A-frame A has an upper end10c and a lower end 10d. A-frame A is supported horizontally fromstructure S by three annular lubrite bearing rings adjacent to the upperend 10c, the lower end 10d and location 10h of A-frame A. The upper andlower bearing rings respectively are denoted 10e and 10l on FIGS. 2 and3. The bearing ring on location 10h is denoted as 10j. Attached to theA-frame A are a number of bearing pads resting against the three annularbearing rings. The upper bearing pad 10f rests againset bearing ring10e. Two lower bearing pads 10k one on each leg of A-frame A restagainst bearing ring 101. Similarly, at the back of the A-frame A,bearing pads 10i, one on each A-frame leg, rest against bearing ring10j. All bearing sections can be fabricated from a nickel aluminumbronze alloy having American Society of Testing Materials specificationB148-C95500, however other bearing materials may be used withoutdeparting from the spirit of the invention. Additionally, rollerbearings or bogies may be used without departing from the spirit of theinvention. It is preferred that a lubricant, not shown, be presentbetween the bearing surfaces. The lubricant should be specified fortemperatures from minus one-hundred degrees Fahrenheit to four-hundreddegrees Fahrenheit and preferably should be an epoxy base, graphite freematerial which will not promote electrolysis in seawater.

Moments imposed on the A-frame A exerted through pin 10b or luffingmeans L, as shown in FIG. 2, are resisted by the combination of uppercontinuous bearing ring 10e and the pair of lower bearing rings 10l and10j. Bearing rings 10e, 10l and 10j additionally facllitate rotation ofA-frame A about the vertical longitudinal axis of offshore structure S.

The weight of A-frame A along with the downward component of loadsaffecting A-frame A are transmitted to structure S via bogies 10n. Eachleg 10p A-frame A (FIG. 3) is supported by a bogie 10n. Each bogie 10nis connected to the A-frame by a ball and socket bearing 10q therebyproviding full articulation to insure equal wheel loading between thebogies 10n in support of A-frame A. The wheels 10r of each bogie 10n areof a special alloy cast steel running on antifriction bearings (notshown) mounted on a stationary shaft 10s secured to the bogie 10n. Asshown in FIG. 2, wheels 10r on each bogie 10n have a flat face and runon an eighteen inch wide alloy steel rail arranged on a circular track10t, for example. Circular track 10t is disposed in a substantiallyhorizontal plane perpendicular to the longitudinal center line ofoffshore structure S. Although each bogie 10n is shown to have twowheels 10r mounted on two separate stationary shafts 10s, otherconfigurations of wheels and shafts may be used without departing fromthe spirit of the invention. Each wheel 10r has a spur gear (not shown)which engages with a pinion (not shown) on the output shaft of a helicalreduction gear 10u powered by a direct current traction motor 10v (FIG.3). An electro-hydraulic brake (not shown) operates on the coupling 10wbetween the motor 10 v and the helical reduction gear 10u. A clutchmechanism of a type known in the art is provlded with each bogie 10n sothat the combination of helical reduction gear 10u and motor 10v withcoupling 10w can selectively drive shafts 10s on each bogie to powerA-frame A along circular track 10t to facilitate the mooring operationas will be discussed hereinbelow. Alternatively, a clutch mechanism (notshown), of a type known in the art, can decouple the drive means on eachbogie (which comprises of reduction gear 10u, coupling 10w and motor10v) from the spur gear (not shown) on each wheel 10r thereby allowingA-frame A to rotate about the longitudinal axis of offshore structure Sdue to the forces imposed by vessel V when it is connected to inner boomI, as will be more fully described hereinbelow. As seen in FIG. 2 bogies10n are disposed beneath and between the pair of lower continuousbearing rings 10j and 10l in a radial direction measured from thelongitudinal centerline of the offshore structure S.

As best seen in FIGS. 2, 3 and 9, luffing means L is mounted on A-frameA and permits outer boom B to pivot about pins 10b which connect outerboom B to A-frame A. Luffing means L includes a luffing winch 20a havingtwin cast wheel drums 20b and 20c with each drum 20b and 20c adapted tocoil ropes 20d and 20e, respectively, in a multilayer fashion. It isunderstood that the luffing means L could employ hydraulic cylinders orother known devices instead of winch 20h without departing from thespirit of the invention. Each rope 20d and 20e passes over a loadequalizing drum 20f (FIG. 3) before being wound up on drums 20b and 20c.In one embodiment, where the maximum capacity of the luffing system is4,500 kips, ropes 20d and 20e consist of two inch diameter wire ropewith each rope arranged in twenty-two falls using four rope pulleyblocks 20g (FIGS. 2 and 9). Luffing winch 20a is driven by a pair oftwin DC motors 20h (FIG. 3) which are connected in a known fashion witha reduction gear via flexible couplings. Alternating current can be usedwithout departing from the sprit of the invention. A double jaw springbrake of a type known in the art (not shown) engages the coupling (notshown) between gear box 20i (FIG. 2) and motor 20h. The spring loadedbrakes can be lifted by electro-hydraulic means or other means known inthe art.

Motors 20h drive drums 20b and 20c at a fixed speed when a vessel is notconnected to outer boom B. The gear box 20i is adapted to provide adirect drive or a four to one speed reduction between motors 20h anddrums 20b and 20c. However, other speed ratios may be used withoutdeparting from the spirit of the invention.

The purpose of luffing system L is two-fold. When a boom I is notconnected to a vessel V, luffing means L supports the weight of outerboom B and inner boom I via pin 20j (FIG. 9) connected to lug 20k at apoint on top of outer boom B approximately two-thirds of the distancefrom pin 10b to the opposite end of outer boom B. Depending onoperational requirements, luffing means L may be employed to raise andlower the assembly of outer boom B and inner boom I to facilitate themooring of vessel V to inner boom I, as will be more fully describedhereinbelow. In the event a vessel V is connected to inner boom I, themooring boom will rotate about the pivot connection 10b as it followsthe movement of vessel V. This movement will tend to slacken ropes 20dand 20e. Since such situations can overstress ropes 20d and 20e bysuddenly applying a tensile force to a slack rope, it is desirable tomaintain ropes 20d and 20e taut at all times that vessel V is connectedto inner boom I. Accordingly, control means 20m (FIG. 2) mounted withmotors 20h can be employed to regulate motors 20h to maintain ropes 20dand 20e taut in response to loads imposed by vessel V tending to slackensaid ropes. Control means 20m varies the field excitation current to theDC shunt wound motors 20 h which are controlled with conventionalsilicon controlled rectifier motor drives. Accordingly, by the variationof the excitation current, in a manner known in the art, the motortorque can be controlled to cause motors 20h to act as torque motors,maintaining a constant tension in the ropes 20d and 20e. Due toenvironmental conditions around the ship, and in order to maintain ropes20d and 20e taut when the vessel is connected to inner boom I, it ispreferred that motors 20h be capable of driving drums 20b and 20c at aspeed of approximately four times the driven speed of drums 20b and 20cwhen a vessel V is not connected to inner boom I. Accordingly, it hasbeen found that a maximum speed of motors 20h corresponding to a tipspeed of the inner boom I of one-hundred feet per minute is adequate tomaintain ropes 20d and 20e in a taut position when a vessel V isconnected to inner boom I.

As shown in FIG. 9 a fixed length service cables 20n are normally stowedattached to outer boom B. In use (FIG. 3), service cables 20n areconnected to the lugs 20p (FIGS. 2, 3) on one end and lugs 20q (FIG. 9)on the other end. With service cables 20n connected ropes 20d and 20ecan be removed for maintenance or replacement. This feature can besignificant in arctic environments due to the isolation of suchfacilities making it difficult to get service help quickly.

As seen in FIG. 2, outer boom B is pivotally mounted to pins 10b closeto the lower end 10d of A-frame A. As best seen in FIGS. 8 and 10, outerboom B is an enclosed elongate structure having rectangularcross-section with vertical sides 30a and 30b and horizontal sides 30cand 30d. Outer boom B further has an outboard end 30e from which innerboom I telescopes. At the opposite end from outboard end 30e, outer boomB has a pair of legs 30f and 30g. Each leg 30f 30g has a rectangularcross-section and is a fabricated steel structure similar to theremainder of outer boom B. Leg 30f terminates in mounting lug 30h andleg 30g terminates in mounting lug 30i. Each of the pins 10b (FIG. 2)retains mounting lug 30h or 30i to one of the mounting lugs 10a onA-frame A. As shown in FIG. 9, fluid transfer means F extends throughoutthe interior of outer boom B from outboard end 30e to legs 30f and 30g.Fluid transfer means F emerges from legs 30f and 30g adjacent mountinglugs 30h and 30i, respectively. In FIG. 9, it can be seen that atposition 30j within outer boom B, fluid transfer means F makes thetransition from the interior of outer boom B to the interior of innerboom I through an orifice in the skin of inner boom I adapted for thispurpose.

The telescoping action of inner boom I inside the outer boom B permitsand compensates for surging motions of vessel V of the type thatotherwise would impart tensile and compressive forces to A-frame A. Inorder to allow the inner boom I to telescope and resist the horizontaland vertical applied loads, a system of support rollers or bogies 30k(FIG. 10) is secured to inner walls 30m, n, p and q. Shock absorptionmeans C is disposed along inner walls 30m and 30p between bogies 30kmounted to said walls. Fluid transfer means F is disposed between bogies30k adjacent inner wall 30q. A plurality of parallel rails 40a areconnected to outer surfaces 40b, c, d and e of inner boom I. The rails40a may be placed in parallel pairs as shown on surfaces 40b and 40d ormay be placed singly as shown on surfaces 40c and 40e. As shown in FIG.9, bogies 30k are connected to outer boom B at two locations, inboardlocation 30r and outboard location 30s.

FIG. 10 illustrates the disposition of bogies 30k at inboard location30r. Due to the presence of a lighter loading, bogies 30k on inner walls30m and 30p each have a single axle and a single wheel 30t. Similarly,bogies 30k are mounted on inner walls 30n and 30q with each bogie 30khaving a single axle with a pair of wheels 30t mounted thereon. Thewheels located on 30g and 30n have fifty ton to thirty-eight toncapacity, respectively. As seen in FIG. 10 all the wheels 30t have flatface treads and are manufactured from cast carbon steel. Wheels 30t runon anti-friction bearings (not shown) carried in the bogie 30k frames.Each wheel 30t rides on a rail 40a. Inboard location 30r features singleaxle bogies mounted to inner walls 30m n, p and q, respectively, asshown in FIG. 10. However, at outboard location 30s the bogies 30kmounted to inner wall 30n have two axles with two fifty ton capacitywheels mounted to each axle. The additional axle and wheels arenecessitated by the higher loads transmitted from the inner boom to theouter boom adjacent outboard end 30e.

As seen in FIGS. 7 through 9, inner boom I is adapted to telescopewithin outer boom B. Inner boom I has an inboard end 40f (FIG. 9) and anoutboard end 40g. As shown in FIG. 10, inner boom I has a rectangularcross-section with outer surfaces 40b, c, d, e describing its outerskin. Outboard end 40g has an arcuate surface 40h (FIG. 7) with anopening 40i whose center is aligned with the longitudinal center planeof inner boom I. Arcuate surface 40h permits boom I to smoothly interactwith a corresponding receptacle on moored vessel V as will be more fullyexplained hereinbelow.

As shown in FIG. 7, inner boom I is an enclosed structure with a dualset of control centers 40j and 40k which can be used to monitor themooring/loading operations. Control center 40j is located inside housing40m and control center 40k is located inside housing 40n. A messengerline 40p used for establishing an initial line connection to vessel Vmay be stored in side housing 40n or in side housing 40m. A messengerline gun 40q may be stored in side housing 40m or side housing 40n.Messenger line gun 40q is portable and can be used to launch messengerline 40p through opening 40i to an awaiting vessel V to initlate themooring procedure as will be more fully described hereinbelow. Themessenger line 40p has a first end which may be connected inside innerboom I and a second end which is launched by messenger line gun 40q tothe vessel V. As shown in FIG. 9, translation means 40 r is locatedwithin inner boom I adjacent inboard end 40f. Translation means 40rincludes a winch 40s (FIG. 10) and rope 40t (FIG. 7) which are used toretrieve messenger line 40p after the messenger line 40p has been shotwith gun 40q to the vessel V. Messenger line 40p is used to bring in apull in line 60b (FIG. 6) from the vessel V in accordance with themooring procedure described hereinbelow. Translation means 40r is alsoused to pull elongated mating link E completely within inner boom I asshown in FIG. 7. Alternatively, using an idler pulley (not shown)located within inner boom I adjacent opening 40i, translation means 40rcan be used to draw elongated mating link E through opening 40i.

As shown in FIG. 9, fluid transfer means F extends substantiallY withininner boom I from position 30j to position 40u, terminating on outersurface 40b of inner boom I at the loading arm means J. Loading armmeans J is a marine loading arm which is fully powered for connectingfluid transfer means F to the piping aboard vessel V. Loading arm meansJ is of a type well known in the art and incorporates a plurality ofswivel movements in perpendicular planes to allow alignment between theend of the fluid transfer means F and the ship board piping on vessel V.Typical of such marine loading arms is a device available from theChiksan Division of Food Machinery Corporation under the designation of"fully powered RCMA". Fluid transfer means F is capable ofsimultaneously handling not only crude oil but gas and gas liquidsthrough separate dedicated lines 80f and 80g.

Elongated mating link E has a first end 50a and a second end 50b (FIG.7). Connection means 50c which preferably is a mounting eye is disposedadjacent first end 50a. Similarly, another connection means 50d which isalso preferably a mounting eye is disposed adjacent second end 50b.Elongated mating link E is further defined by tapered surface 50e,annular surface 50f, and radial surface 50g. Radial surface 50g forms astep adjacent an engagement segment 50h which preferably has arectangular cross-section. An elliptical section 50i is disposedadjacent engagement segment 5oh and defines a elliptical surface 50jtherebetween. As will be more fully discussed hereinbelow, releasableengagement means R with the vessel V (FIG. 6) is adapted to engageelongated mating link E adjacent engagement segment 50h between step 50gand radial surface 50j. Section 50i has an elliptical cross-section tofacilitate alignment of engagement segment 50h with the releasableengagement means R aboard the vessel V.

As previously stated, translation means 40r can be employed using rope40t connected to connecting means 50d adjacent second end 50b to movefirst end 50a through opening 40i (FIG. 7 and FIG. 9). Elongated matinglink E can move through opening 40i until spherical contact surface 50kdisposed adjacent elliptical section 50i comes in contact with arcuatesurface 40v inside inner boom I (FIG. 7). As shown in FIGS. 6 and 7,spherical contact surface 50k is defined by a cord 50m which is longerthan the opening 40i thereby allowing elongated mating link E to beretained by inner boom I due to the interaction between sphericalcontact surface 50k and arcuate surface 40v. Accordingly, sphericalcontact surface 50k represents the outer travel stop of elongated matinglink E as it moves through opening 40i. It should be noted thatelliptical section 50i is mounted to spherical contact surface 50k insuch a manner that the longitudinal axis of elliptical section 50i isdisposed perpendicular to the plane of cord 50m. As can be seen in FIG.6, elongated mounting link E is pivotally mounted with respect to innerboom I when spherical contact surface 50k engages arcuate surface 40v.Finally, elongated mating link E has a square cross-section 50n adjacentspherical contact surface 50k so that when elongated mating link E isstored fully within inner boom I it will remain therein without rollingfrom side to side.

As seen in FIG. 6, releasable engagement means R includes a tractionwinch 60a, a pull in line 60b, and a chain stopper 60c of a type knownin the art. Pull in line 60b is operably connected to traction winch 60afor drawing the vessel V to inner boom I. In mooring the vessel V toinner boom I, messenger line 40p is shot over to vessel V via gun 40q.Alternatively, vessel V may pass at ninety degrees to the centerline ofthe longitudinal axis of inner boom I whereupon messenger line 40p maybe dropped through opening 40i onto the deck of vessel V.

Having secured the messenger line 40p on the deck of vessel V, themessenger line is brought through opening 60d in the bow and deck ofvessel V. The messenger line 40p is then connected to pull in line 60b.Traction winch 60a is employed to pay out pull in line 60b, whilesimultaneously, translation means 40r within inner boom I reels inmessenger line 40p with pull in line 60b connected thereto. Thisprocedure will prevent any of the lines from coming into contact withthe water or the ice surface. When translation means 40r brings one endof pull in line 60b into inner boom I through opening 40i, the pull inline 60b is connected to connection means 50c adjacent first end 50a ofelongated mating link E (see FIG. 7). With the pull in line 60bconnected to connection means 50c on elongated mating link E, thetraction winch can be operated to initially pull elongated mating link Ethrough opening 40i until spherical contact surface 50k contacts arcuatesurface 40v. Subsequently, upon further operation of traction winch 60a,vessel V will be drawn toward inner boom I. However, it is preferredthat translation means 40r be employed after connecting pull in line 60bto connecting means 50c to initially move elongated mating link E untilspherical contact surface 50k contacts arcuate surface 40v. Usingtranslation means 40r to bring spherical contact surface 50k in contactwith arcuate surface 40v avoids transmitting shocks to inner boom I bythe sudden contact between spherical contact surface 50k and arcuatesurface 40v. Additionally, if vessel V is not closely aligned with thelongitudinal center line of inner boom I but is offset several degrees,traction winch 60a will not be able to pull elongated mating link Ethrough opening 40i. Therefore, it is preferred that, upon bringingspherical contact surface 50k into contact with arcuate surface 40vusing translation means 40r, traction winch 60a on vessel V be employedto reel in pull in line 60c thereby drawing bow 60e toward inner boom I.As previously described, luffing means L can be used to initially alignopening 40i with opening 60d in vessel V before traction winch 60a isemployed to draw vessel V toward inner boom I.

As seen in FIG. 6, elliptical section 50i interacts with the curvedsurface forming opening 60d to align square engagement segment 50h withpawls 60f connected to chain stopper 60c. Pawls 60f are hydraulicallyactuated by rods 60g. As shown in FIG. 6, each rod 60g selectivelyraises a pawl 60f adjacent square engagement section 50h until pawls 60fcome in contact with step 50g (FIG. 7). Upon successful engagementbetween pawls 60f and elongated mating link E, pull in line 60b may bedisconnected from elongated mating link E. Alternatively, the pull inrope 60b may be left connected to the mating link E, so to enable thevessel V and mooring boom I to reconnect easier after a temporarydisengagement. With elongated mating link E secured within vessel V,arcuate surface 40h remains in contact with bow 60e despite any movementof the vessel V.

In the event a sudden disconnection is required between inner boom I andthe vessel V, suitable controls, of a type known in the art, can beengaged to operate rods 60g to retract pawls 60f thereby allowingelongated mating link E to be withdrawn from bow 60e of vessel V uponastern movement of vessel V. Prior to this operation, fluid transfermeans F would be disconnected from vessel V at loading arm means J.

When vessel V is connected to inner boom I, changing environmentalconditions may cause vessel V to move toward or away from inner boom I.Such movement by vessel V exerts a component of force directed along thelongitudinal axis of inner boom I. Similarly, when vessel V pulls awayfrom inner boom I a tensile force having a component along thelongitudinal axis of inner boom I is exerted on inner boom I by vesselV. To compensate for such tensile and compressive forces exerted oninner boom I by vessel V, shock absorption means C is disposed betweeninner boom I and outer boom O to dampen such sudden movements.

As shown in FIGS. 8, 9 and 11, a crosshead 70a is connected to inboardend 40f of inner boom I. A pair of single acting pneumatic cylinders 70band 70f are connected to inner wall 30p. Similarly, a pair of singleacting pneumatic cylinder 70c and 70g are connected to inner wall 30m(FIG. 10). Pneumatic cylinders 70b and 70c each have a piston rod 70dand 70e, respectively, extending therefrom. Piston rods 70d and 70eabutt crosshead 70a. Accordingly, upon application of a tensile force byvessel V on inner boom I, outward telescoping of inner boom I from outerboom B will be dampened by pneumatic cylinders 70b and 70c due to theinteraction of crosshead 70a with piston rods 70d and 70e. Conversely,single acting pneumatic cylinders 70f and 70g (FIG. 8), which aresecured to inner walls 30p and 30m of outer boom B will resistcompressive forces applied by vessel V on inner boom I tending totelescope inner boom I into outer boom B, due to the interaction ofpiston rods 70h and 70i extending respectively from cylinders 70f and70g and in contact with crosshead 70a.

As seen in FIG. 11, cylinders 70b, c, f, and g, each have a piston 70jmounted therein operably connected to the respective piston rod. Inorder to avoid the use of any external bank of air bottles to accumulatecompressed gas 70k (disposed within cylinders 70b, c, f and g adjacentto their respective pistons 70j), each piston rod 70d, e, h and i ishollow defining a cavity 70l therein. The cavity 70l in each piston rodcommunicates with the fluid on the opposite side of the piston so thatupon movement of crosshead 70a, the compressed gas 70k can flow intocavity 70l. Utilization of the volume of cavity 70l in this manner,eliminates the need for an external bank of pressure vessels or bottlesfor storage of the compressed gas 70k.

It should be noted that upon application of a tensile force by thevessel V on inner boom I which results in movement of crosshead 70atoward outboard end 30e of outer boom B, piston rods 70h and 70i will bedisengaged from crosshead 70a. Similarly upon application of acompressive force by vessel V on inner boom I which results in movementof crosshead 70a toward legs 30f and 30g, piston rods 70d and 70e willnot be in contact with crosshead 70a. Control means 70n can be locatedin control center 40k (FIG. 7) or aboard offshore structure S (notshown) for monitoring the operation of shock absorber means C. Controlmeans 70n applies a preload of pneumatic pressure to all of cylinders70b, 70c, 70f and 70g so that no movement of the crosshead can takeplace until a sustained tensile or compressive force of around onehundred tons is imposed by the vessel V on inner boom I. Thus both thepretension and damping of the mooring system can be continuouslyadjusted with control means 70n. Control system C employs conventionalmechanical and electrical control components to accomplish the controlfunction, and any suitable conventional control components may be used.Control means 70n is adapted to permit the level of sustained externalforce necessary to initiate movement of crosshead 70a to be changed evenwhile vessel V is connected to inner boom I. It should be understoodthat control means 70n can be readily adapted to suit other levels ofsustained external forces without departing from the spirit of theinvention. It is preferred, for example, that pistons 70j have a strokeof as long as twenty feet for all cylinders 70b, 70c, 70f and 70g andthat shock absorption means C have a capacity of 2,500 kips whenresisting tensile forces applied by vessel V and a capacity of 500 kipsin resisting compressive forces applied by vessel V on inner boom I.

The transfer of fluids from offshore structure S to the vessel V andvice versa can begin once vessel V is moored to inner boom I. Fluidtransfer means F includes a circular fluid loading header 80a located inan enclosure 100g (FIG. 2) secured to offshore structure S and connectedto storage facilities on the platform (not shown). Circular fluidloading header 80a has a plurality of outlets 80b in fluid communicationtherewith (FIGS. 4 and 5). Each of said outlets 80b has a swivel joint80c, shut off valve 80d and a coupling half 80e. As seen in FIGS. 8 and9, a pair of fluid loading lines 80f and 80g extend from loading armmeans J through the interior of inner boom I from position 42 toposition 30j. Fluid loading lines 80f and 80g then continue in theinterior space between inner boom and outer boom B whereupon line 80fhas a pluarality of pairs of swivel joints 80i and line 80g has asimilar number of pairs of swivel joints 80k nested between swiveljoints 80i as shown in FIG. 8. As seen in FIG. 9, each pair of swiveljoints 80i and 80k is independently supported within outer boom B formotion in a direction parallel to the longitudinal axis of outer boom B.Accordingly, when inner boom I telescopes into or out of outer boom B,the overall length of lines 80f and 80g can be extended or shortened, asneeded, via the pairs of swivel joints 80i and 80k on lines 80f and 80grespectively.

Referring now to FIG. 9, the piping between a pair of swivel joints 80ior 80k has an extension 80l which is adapted to engage track 80n forsupport throughout the range of movement within outer boom B. Althoughextension 80l is connected to one of lines 80f and 80g, in effect bothlines are simultaneously supported due to a dummy pipe 80p having aswivel joint 80r therein. It is preferred that lines 80f and 80g besixteen inch pipe although other sizes may be employed depending on thepumping rate desired into vessel V. At least one smaller, six inch,fluid transfer line 80s follows substantially the same path as lines 80fand 80g from loading arm means J to A-frame A. Since fluid transfer lineS is of a smaller diameter than lines 80f and 80g the requiredflexibility for fluid transfer one 80s wlthin outer boom B as a resultof the telescoping motion of inner boom I can be provided for by using aflexible segment 80t (FIG. 9) which can be supported from the pairs ofswivel joints 80i and 80k. Fluid transfer line 80s is used to pumpdiesel, water and other fluids from the vessel V onto the offshorestructure S separately or in conjunction with the transfer of fluidsfrom offshore structure S via lines 80f and 80g. This can alleviate theneed for separate supply vessels.

As shown in FIG. 4, line 80g extends through leg 30g and via swiveljoints 80u into the interior of A-frame A. Line 80f is similarlyconstructed and passes through leg 30f and enters the interior ofA-frame A via pipe segments connected by swivel joints 80v (FIG. 5).Auxiliary fluid transfer lines 80s are employed, as shown in FIG. 5.Each auxiliary fluid transfer line 80s can extend through leg 30f or 30gand via a flexible segment 80w enter the interior of A-frame A. Uponemerging from adjacent the upper end 10c of A-frame A, auxiliary fluidtransfer line 80s can be connected to a ring header (not shown) having aplurality of outlets 80y (FIG. 4) for transferring potable water anddiesel fuel from the vessel V to the offshore structure S. Due to theintermittent nature of the operation of loading potable water and dieselfuel to the structure S, lines 80s must be manually disconnected andreconnected in the event vessel V weather vanes about structure S beyonda predetermined operational range causing A-frame A to move therewith.It is preferred to have at least two fluid transfer lines 80s with onededicated to potable water service and the other for transferring dieselfuel and the like. Accordingly, a flexible segment 80z is provided toconnect each line 80s to an outlet 80y (FIGS. 4 and 5).

As seen in FIG. 5 both lines 80f and 80g emerge from within A-frame A atpoints 80aa and 80bb, respectively. Thereafter, in order to allow lines80f and 80g sufficient flexibility to remain connected to coupling half80e as A-frame A travels on circular track 10t, both lines 80f and 80gemploy a plurality of swivel joints 80cc (FIG. 4) disposed between thestructure S and the inboard side 10k of A-frame A.

As shown in FIG. 4, shuttle means T is secured to the offshore structureS. Shuttle means T includes a circular track 90a upon which ride twomotorized trolleys 90b each of which supports one of fluid loading lines80f or 80g. One motorized trolley 90b is linked to line 80g via link90c. Line 80f (not shown in FIG. 4) is similarly supported with theother trolley 90b. Riding with each motorized trolley 90b is alignmentmeans W. Alignment means W is mounted to each motorized trolley 90b forindependently rotating lines 80f or 80g about swivel joint 90dd.Although only line 80g is shown in FIG. 4, line 80f has a similar swiveljoint 90dd which is operated by alignment means W connected to anothermotorized trolley 90b. Lines 80f and 80g each terminate in a couplinghalf 80ee (FIG. 4) which is designed to automatically mate and couplefrom coupling half 80e on each outlet 80b. Coupler means X with eachoutlet 80b selectively rotates swivel joint 80c for alignment betweencoupling half 80e and coupling half 80ee. Control means Y with each line80f and 80g senses the angular deflection between pipe segment 80ff and80gg (FIG. 4) to determine the opportune time for coupling or decouplinghalf 80ee from a given mating coupling half 80e. Although FIG. 5 showslines 80f and 80g connected to adjoining outlets 80b, it is preferredthat lines 80f and 80g be staggered so that there will be one unusedoutlet 80b between connected lines 80f and 80g.

With the vessel V connected to inner boom I and free to weathervane withrespect to the offshore structure S, movement of A-frame A will causeangular displacement between pipe segments 80ff and 80gg on each of theconnected lines 80f and 80g. Accordingly, it is preferred that as vesselV rotates in a given direction about the structure S that at the instantthat one loading line, line, 80f for example, reaches its maximumextension, as represented by a preset angular deflection betweensegments 80ff and 80gg, that the other loading line 80g be at the pointof least deflection as represented by segments 80ff and 80gg beingdisposed in the same vertical plane. In the event vessel V continues toweathervane in a given direction after control means Y has sensed thatone of the connected lines 80f and 80g has reached its maximumextension, control means Y activates coupler means X and alignment meansW thereby rotating coupling half 80e on the outlet 80b which is about tobe disconnected from a loading line 80f or 80g. When coupler means X hasoriented the coupling half 80e along a tangent line to the perimeter ofstructure S, further movement of A-frame A in the same direction causescoupler means X to close valve 80d and decouple coupling half 80e fromcoupling half 80ee. Upon decoupling, a given loading line 80f or 80g isdriven by shuttle means T, as commanded by control means Y, to bringcoupling half 80ee to the next adjacent coupling half 80e in thedirection of motion of a A-frame A. When shuttle means T has broughtcoupling half 80ee close to the next adjacent coupling half 80e in thedirection of motion of A-frame A, control means Y will allow alignmentmeans W to orient coupling half 80ee and coupler means X to aligncoupling half 80e at the next adjacent outlet 80b so that a reconnectioncan be made. During the time shuttle means T drives line 80f or 80g withrespect to A-frame A, the other loading line is still in service pumpingfluids from the offshore structure S to the vessel V. Accordingly, withthe angular displacement between segments 80ff and 80gg beingsufficiently staggered, control means Y maintains one of loading lines80f and 80g in service at all times. Coupling and decoupling of loadinglines 80f and 80g and auxiliary line 80s is done within an enclosedstructure 100g (FIG. 2) and is designed to be a dry-break insuringminimal spillage of the fluids transferred. The enclosure 100g minimizesicing on the connections and can retain spillage in an emergency toprevent pollution.

In an emergency situation requiring quick disconnection, loading armmeans J can disconnect lines 80f, g, and s and rods 60g can be actuatedto release elongated mating link E from vessel V after an audible andvisual warning. Upon application of astern power the vessel V can moveaway from inner boom I.

Access is provided from structure S through ladder 100b (FIG. 2) intoenclosure 100g. An operator may gain access into the top of A-frame Athrough a doorway (not shown) which allows access between enclosure 100hand enclosure 100c. Elevator 100e can be ridden down shaft 100d to gainaccess to platform 100f. From platform 100 f access can be had to anopening in enclosed by leg 30g for access into the outer boom B. Usingstair 100h (FIG. 9) personnel and equipment can be transferred fromouter boom B to inner boom I. Additional platforms can be provided atthe end of inner boom I to allow access to vessel V from inner boom I,thereby allowing vessel V to act as a personnel and consumables supplyvessel.

The foregoing disclosure and description of the invention areillustrative and explanatory thereof, and various changes in the size,shape and materials, as well as in the details of the illustratedconstruction may be made without departing from the spirit of theinvention.

We claim:
 1. A mooring system for connecting a vessel having a mooringreceptacle to a fixed noncompliant offshore structure comprising:boommeans mounted to said structure for establishing an extensible,semi-rigid coupling between the vessel and the structure, said boommeans further comprising:an outer boom pivotally mounted to thestructure for movement in a plane parallel to the longitudinal axis ofthe offshore structure and for movement about the periphery of thestructure in a plane perpendicular to the longitudinal axis of thestructure; an inner boom slidably mounted within said outer boom, andadapted for telescoping motion therewith in response to vessel movement;said inner boom having an inboard end disposed within said outer boom,and an outboard end extending beyond said outer boom, said outboard endhaving an opening formed therein and adapted for contact with a mooringreceptacle on the vessel; luffing means for coarsely aligning saidopening in said inner boom with the mooring receptacle of the vessel; anelongated mating link retained by said inner boom and adapted forselective extension through said opening in said inner boom to engagethe mooring receptacle on the vessel, said elongated mating linkengaging said end of said inner boom so as to provide a pivotal mountingtherebetween with respect to the longitudinal axis of said inner boomwhen said elongated link is extended through said opening in said innerboom; shock absorption means with said inner and outer boom fordampening tensile and compressive forces exerted by the vessel on saidinner boom in a direction parallel to the longitudinal axis of saidinner boom; and whereby said inner boom remains in contact with themooring receptacle on the vessel notwithstanding movement of the vessel.2. The system of claim 1 further including:means with the vessel forreleasably engaging said elongated mating link.
 3. The system of claim2, wherein said shock absorption means further includes:a crossheadmounted to the inboard end of said inner boom; a compression pneumaticcylinder connected to said outer boom, having a piston rod extendingtherefrom and abutting said crosshead to resist compressive forcesexerted by the vessel which tend to force said inner boom to telescopeinto said outer boom; and a tension pneumatic cylinder connected to saidouter boom and having a piston rod extending therefrom and abutting saidcrosshead to resist tensile forces exerted by the vessel which tend toextend said inner boom from said outer boom.
 4. The system of claim 3wherein:said tension and compression pneumatic cylinders each have apiston connected to said piston rod therein; said piston rod in saidtension and compression pneumatic cylinders each defines a cavitytherein; a compressible fluid disposed in said tension and compressionpneumatic cylinders adjacent said piston therein; whereupon the exerciseof a tensile force by the vessel on said inner boom said piston, in saidtensile pneumatic cylinder, compresses said compressible fluid thereininto said cavity in said piston rod therein, and upon the exercise of acompressive force by the vessel on said inner boom said piston, in saidcompression cylinder compresses said compressible fluid therein intosaid cavity in said piston rod therein; thereby allowing said tensionand compression hydraulic cylinders to take the place of an externalcompressed fluid accumulator vessel outside of said tension andcompression hydraulic cylinders.
 5. The system of claim 4 wherein saidshock absorption means further includes:control means for selectivelypressurizing said compressible fluid in both said tension andcompression pneumatic cylinders thereby preventing movement of saidpiston in said tension and compression pneumatic cylinders until apreset sustained unidirectional force exerted by the vessel on saidinner boom is attained, said control means allowing continuousadjustment of the dampening effect of said compression and tensionpneumatic cyliders.
 6. The system of claim 5 wherein:said piston in saidtension and compression pneumatic cylinders has a stroke length of asmuch as 20 feet.
 7. The system of claim 6 wherein said elongated matinglink further includes:a first end adapted to be inserted into themooring receptacle of the vessel further including: connection means forallowing said releasable engagement means with said vessel to draw saidvessel to said inner boom; an engagement segment defining a stepadjacent thereto, said releasable engagement means engaging said stepadjacent said engagement segment to retain said elongated mating link tothe vessel.
 8. The system of claim 7 wherein said inner boom furtherincludes:a messenger line connected at a first end to said inner boom;means for delivering a second end of said messenger line from said innerboom to the vessel; and, said releasable engagement means with thevessel further includes; a pull in line adapted to be selectivelyconnected to said messenger line and said connection means on said firstend of said elongated mating link; a traction winch for selectivelyreeling in or paying out said pull in line; a chain stopper adapted toengage said step on said first end of said elongated mating link toretain said mating link to the vessel.
 9. The system of claim 8wherein:the mooring receptacle on the vessel further comprises anopening formed on the bow of the vessel; said elongated mating linkfurther includes:connection means adjacent a second end for selectivelymoving said elongated mating link with respect to said inner boom; aspherical contact surface adjacent said second end defining a chordlarger than said opening in said inner boom, thereby representing theouter travel stop of said elongated mating link with respect to saidinner boom; an elliptical section between said spherical contact surfaceand said engagement segment, to contact the bow of the vessel therebyfacilitating alignment between said engagement segment of said elongatedmating link and said chain stopper, as said elongated mating link entersthe opening in the bow of the vessel due to the reeling in motion ofsaid traction winch; and means with said inner boom selectivelycooperating with said connection means adjacent said second end of saidmating link for translating said spherical contact surface into and outof contact with said inner boom adjacent said opening therein and forpulling in said messenger line with said pull in line connected thereto.10. The system of claim 9 wherein:said elongated link can be pulledcompletely into said inner boom with said moving means disposed withinsaid inner boom; whereupon when said translating means is disabled andsaid pull-in line is connected to said connection means on said firstend of said mating link, said traction winch can draw said mating linkthrough said opening in said inner boom until said spherical contactsurface is in contact with said inner boom whereupon said traction winchcan draw the vessel toward said step on said mating link until saidchain stopper can operably engage said step adjacent said engagementsegment.
 11. The system of claim 10 further including:an A-frame mountedto the offshore structure and adapted to rotate 360 degrees about thelongitudinal axis of the offshore structure; said outer boom pivotallymounted to said A-frame, said luffing means mounted with said A-framefor pivoting said outer boom.
 12. The system of claim 11 wherein saidluffing means further includes:a luffing winch, a plurality of pulleysdisposed on said A-frame and said outer boom; a plurality of ropesdriven by said luffing winch over said pulleys for pivoting said outerboom with respect to said A-frame; control means with said luffing winchfor maintaining tensile force on said plurality of ropes in response tomotions of the vessel which tends to slacken said ropes.
 13. The systemof claim 12 wherein said luffing means further includes:a plurality ofservice cables selectively mounted in a first position wherein saidcables are secured to said outer boom and a second position wherein saidcables are connected between said pulleys on said A-frame and said outerboom thereby taking the weight of said outer boom off of said ropesdriven by said luffing winch so that said driven ropes can be maintainedand replaced.
 14. The system of claim 13 wherein said luffing winchfurther includes:a two speed gear box; and said control meansselectively meshes the gears in said gearbox so that said luffing winchcan pivot said outer boom faster when a vessel is connected thereto thanwhen said plurality of ropes supports the weight of said inner and outerboom thereby increasing the responsiveness of said control means to anypotential slack in said plurality of ropes.
 15. The system of claim 14further including:a circular track disposed in said offshore structurein a plane perpendicular to the longitudinal axis of the offshorestructure; at least one bogie pivotally connected to the lower end ofsaid A-frame said bogie having at least one axle with at least one wheelmounted thereto, said wheels in contact with said circular track; saidouter boom pivotally connected to said A-frame adjacent its lower end;an upper continuous annular bearing pad between the upper end of saidA-frame and the offshore structure; a pair of lower continuous annularbearing pads adjacent said lower end of said A-frame and the offshorestructure, said bogie on said A-frame being disposed between and beneathsaid pair of lower continuous bearing pads in a radial direction withrespect to the motion of said A-frame.
 16. The system of claim 15further including:a circular fluid loading header on the offshorestructure having a plurality of outlets, each of said outletsterminating in a coupling pivotally mounted for rotation about an axissubstantially parallel with the longitudinal axis of said offshorestructure; a plurality of fluid loading lines each having a couplingadapted to be selectively mated to the coupling on each outlets in saidcircular fluid loading header, said loading lines extending fromadjacent said outlets in said circular fluid loading header, throughsaid A-frame and said inner and outer booms to the outboard end of saidinner boom; an auxiliary fluid transfer line extending in a pathadjacent to said fluid loading lines from the outboard end of said innerboom to adjacent the offshore structure for transferring fluids from thevessel to the offshore structure; and loading arm means for connectingsaid fluid loading lines and said auxiliary fluid transfer line betweenthe outboard end of said outer boom to the vessel.
 17. The system ofclaim 16 further including:a plurality of swivel joints in each fluidloading line between said A-frame the offshore structure, therebyallowing each fluid loading line to remain connected to one of saidoutlets in said circular fluid loading header for a fixed displacementof said A-frame circumferentially about the offshore structure; drivemeans with said bogie on said A-frame for selectively driving saidA-frame along said circular track, said drive means adapted to bedisabled when the vessel is connected to said inner boom, whereupon saidvessel can direct the motion of said A-frame along said circular track;coupler means with said outlets on said circular fluid loading headerfor automatically coupling and decoupling each said fluid loading linesto any of said outlets on said circular fluid loading header and forrotating each said outlets in said circular fluid loading header inconjunction with said coupling and decoupling; shuttle means movablymounted to the offshore platform for independently moving each of saidfluid loading lines circumferentially about the offshore structurefaster than said A-frame, after said coupler means decouples each saidfluid loading line from an outlet on said circular loading header; andalignment means movably mounted to said shuttle means for traveling withone of said swivel joints on each said fluid loading line, for operablyrotating at least one of said swivel joints on each fluid loading lineto facilitating alignment of said coupling on each of said fluid loadingline to the next adjacent coupling on an outlet on said circular loadingheader approached by said shuttle means.
 18. The system of claim 17further including:loading system control means mounted to the offshorestructure for sensing the extension of each of said fluid loading linesadjacent said swivel joints and activating said coupler means, shuttlemeans and alignment means thereby preventing overextension of each saidloading line due to movement of said A-frame along said circular trackcaused by the vessel connected to said outer boom; and said fluidloading lines are circumferentially staggered with respect to the motionof said A-frame thereby allowing said loading system control means tomaintain at least one fluid loading line coupled to one of said outletson said circular fluid loading header so that flow from the offshorestructure to the vessel is not completely interrupted as the vesselweathervanes about the offshore structure.
 19. The system of claim 18wherein:said fluid loading lines and said fluid transfer line extendsubstantially within said inner and outer boom and said A-frame therebyshielding said lines from environmental conditions adjacent the offshorestructure.
 20. The system of claim 19 wherein each fluid loading linefurther includes:a plurality of pairs of swivel joints disposed withinsaid outer boom each said pair of swivel joints supported by said outerboom for slidable motion in a direction parallel to the longitudinalaxis of said outer boom, said pairs of swivel joints allowingcompensation in the length of each said fluid loading line within saidouter boom due to compressive and tensile forces exerted by the vesselon said inner boom in a direction parallel to the longitudinal axis ofsaid inner boom.
 21. The system of claim 20 further including:aplurality of tracks mounted to said inner boom; a plurality of bogiesdisposed in at least two spaced locations with respect to longitudinalaxis of said outer boom, said bogies connected to said outer boom andeach having at least one axle with at least one wheel mounted thereon,each of said wheels in rolling contact with one of said tracks on saidinner boom thereby permitting said inner boom to telescope with respectto said outer boom.
 22. The system of claim 21 wherein:the outboard endof said inner boom is arcuate thereby allowing said inner boom tosmoothly interact with the bow of the vessel in response to vesselmovement.
 23. The system of claim 2 wherein said elongated mating linkfurther includes:a first end adapted to be inserted into the mooringreceptacle of the vessel further including: connection means forallowing said releasable engagement means with said vessel to draw saidvessel to said inner boom; an engagement segment defining a stepadjacent thereto, said releasable engagement means engaging said stepadjacent said engagement segment to retain said elongated mating link tothe vessel.
 24. The system of claim 23 wherein said inner boom furtherincludes:a messenger line connected at a first end to said inner boom;means for delivering a second end of said messenger line from said innerboom to the vessel; and, said releasable engagement means with thevessel further includes; a pull in line adapted to be selectivelyconnected to said messenger line and said connection means on said firstend of said elongated mating link; a traction winch for selectivelyreeling in or paying out said pull in line; a chain stopper adapted toengage said step on said first end of said elongated mating link toretain said mating link to the vessel.
 25. The system of claim 24wherein:the mooring receptacle on the vessel further comprises anopening formed on the bow of the vessel; said elongated mating linkfurther includes:connection means adjacent a second end for selectivelymoving said elongated mating link with respect to said inner boom; aspherical contact surface adjacent said second end defining a chordlarger than said opening in said inner boom, thereby representing theouter travel stop of said elongated mating link with respect to saidinner boom; an elliptical section, between said spherical contactsurface and said engagement segment, to contact the bow of the vesselthereby facilitating alignment between said engagement segment of saidelongated mating link and said chain stopper, as said elongated matinglink enters the opening in the bow of the vessel due to the reeling inmotion of said traction winch; and means with said inner boomselectively cooperating with said connection means adjcent said secondend of said mating link for translating said spherical contact surfaceinto and out of contact with said inner boom adjacent said openingtherein and for pulling in said messenger line with said pull in lineconnected thereto.
 26. The system of claim 25 wherein:said elongatedlink can be pulled completely into said inner boom with said movingmeans disposed within said inner boom; whereupon when said translationmeans is disabled and said pull-in line is connected to said connectionmeans on said first end of said mating link, said traction winch candraw said mating link through said opening in said inner boom until saidspherical contact surface is in contact with said inner boom whereuponsaid traction winch can draw the vessel toward said step on said matinglink until said chain stopper can operably engage said step adjacentsaid engagement segment.
 27. The system of claim 2 further including:aplurality of tracks mounted to said inner boom; a plurality of bogiesdisposed in at least two spaced locations with respect to longitudinalaxis of said outer boom, said bogies connected to said outer boom andeach having at least one axle with at least one wheel mounted thereon,each of said wheels in rolling contact with one of said tracks on saidinner boom thereby permitting said inner boom to telescope with respectto said outer boom.
 28. The system of claim 2 further including:anA-frame mounted to the offshore structure and adapted to rotate 360degrees about the longitudinal axis of the offshore structure; saidouter boom pivotally mounted to said A-frame, said luffing means mountedwith said A-frame for pivoting said outer boom.
 29. The system of claim28 wherein said luffing means further includes:a luffing winch, aplurality of pulleys disposed on said A-frame and said outer boom; aplurality of ropes driven by said luffing winch over said pulleys forpivoting said outer boom with respect to said A-frame; control meanswith said luffing winch for maintaining tensile force on said pluralityof ropes in response to motion of the vessel which tends to slacken saidropes.
 30. The system of claim 29 wherein said luffing means furtherincludes:a plurality of service cables selectively mounted in a firstposition wherein said cables are secured to said outer boom and a secondposition wherein said cables are connected between said pulleys on saidA-frame and said outer boom thereby taking the weight of said outer boomoff of said ropes driven by said luffing winch so that said driven ropescan be maintained and replaced.
 31. The system of claim 29 wherein saidluffing winch further includes:a two speed gear box; and said controlmeans selectively meshes the gears in said gearbox so that said luffingwinch can pivot said outer boom faster when a vessel is connectedthereto than when said plurality of ropes supports the weight of saidinner and outer boom thereby increasing the responsiveness of saidcontrol means to any potential slack in said plurality of ropes.
 32. Thesystem of claim 28 further including:a circular track disposed in saidoffshore structure in a plane perpendicular to the longitudinal axis ofthe offshore structure; at least one bogie pivotally connected to thelower end of said A-frame said bogie having at least one axle with atleast one wheel mounted thereto, said wheels in contact with saidcircular track; said outer boom pivotally connected to said A-frameadjacent its lower end; an upper continuous annular bearing pad betweenthe upper end of said A-frame and the offshore structure; a pair oflower continuous annular bearing pads adjacent said lower end of saidA-frame and the offshore structure, said bogie on said A-frame beingdisposed between and beneath said pair of lower continuous bearing padsin a radial direction with respect to the motion of said A-frame. 33.The system of claim 32 further including:a circular fluid loading headeron the offshore structure having a plurality of outlets, each of saidoutlets terminating in a coupling pivotally mounted for rotation aboutan axis substantially parallel with the longitudinal axis of saidoffshore structure; a plurality of fluid loading lines each having acoupling adapted to be selectively mated to the coupling on each outletin said circular fluid loading header, said loading lines extending fromadjacent said outlets in said circular fluid loading header, throughsaid A-frame and said inner and outer booms to the outboard end of saidinner boom; an auxiliary fluid transfer line extending in a pathadjacent to said fluid loading lines from the outboard end of said innerboom to adjacent the offshore structure for transferring fluids from thevessel to the offshore structure; and loading arm means for connectingsaid fluid loading lines and said auxiliary fluid transfer line betweenthe outboard end of said outer boom to the vessel.
 34. The system ofclaim 33 further including:a plurality of swivel joints in each fluidloading line between said A-frame and the offshore structure, therebyallowing each fluid loading line to remain connected to one of saidoutlets in said circular fluid loading header for a fixed displacementof said A-frame circumferentially about the offshore structure; drivemeans with said bogie on said A-frame for selectively driving saidA-frame along said circular track, said drive means adapted to bedisabled when the vessel is connected to said inner boom, whereupon saidvessel can direct the motion of said A-frame along said circular track;coupler means with said outlets on said circular fluid loading headerfor automatically coupling and decoupling each said fluid loading linesto any of said outlets on said circular fluid loading header and forrotating each said outlets in said circular fluid loading header inconjunction with said coupling and decoupling; shuttle means movablymounted to the offshore platform for independently moving each of saidfluid loading lines circumferentially about the offshore structurefaster than said A-frame, after said coupler means decouples each saidfluid loading line from an outlet on said circular loading header; andalignment means movably mounted to said shuttle means for traveling withone of said swivel joints on each said fluid loading line, for operablyrotating at least one of said swivel joints on each said fluid loadingline, thereby facilitating alignment of said coupling on each of saidfluid loading line to the next adjacent coupling on an outlet on saidcircular loading header approached by said shuttle means.
 35. The systemof claim 34 further including:loading system control means mounted tothe offshore structure for sensing the extension of each of said fluidloading lines adjacent said swivel joints and activating said couplermeans, shuttle means and alignment means thereby preventingoverextension of each said loading line due to movement of said A-framealong said circular track caused by the vessel connected to said outerboom; and said fluid loading lines are circumferentially staggered withrespect to the motion of said A-frame thereby allowing said loadingsystem control means to maintain at least one fluid loading line coupledto one of said outlets on said circular fluid loading header so thatflow from the offshore structure to the vessel is not completelyinterrupted as the vessel weathervanes about the offshore structure. 36.The system of claim 35 wherein:said fluid loading lines and said fluidtransfer line extend substantially within said inner and outer boom andsaid A-frame thereby shielding said lines from environmental conditionsadjacent the offshore structure.
 37. The system of claim 36 wherein eachfluid loading line further includes:a plurality of pairs of swiveljoints disposed within said outer boom each said pair of swivel jointssupported by said outer boom for slidable motion in a direction parallelto the longitudinal axis of said outer boom, said pairs of swivel jointsallowing compensation in the length of each said fluid loading linewithin said outer boom due to compressive and tensile forces exerted bythe vessel on said inner boom in a direction parallel to thelongitudinal axis of said inner boom.
 38. The system of claim 1wherein:the outboard end of said innner boom is arcuate thereby allowingsaid inner boom to smoothly interact with the bow of the vessel inresponse to vessel movement.